The invention is directed to a method with which autonomous mobile units can be brought into a parked position.
Autonomous mobile units can, for example, be employed in office, hospital or industrial environments in order to carry out simple tasks such as, for example, transport, remote manipulation or cleaning jobs. Upon utilization of such autonomous mobile robots, for example, it is desirable that these can dock precisely in order, for example, to be able to accept or hand over goods in a docking station, change a battery or, for example, replace the cleaning device in a cleaning machine. Another docking case can occur when the autonomous mobile unit is to travel into a garage in which it waits until further activity requests are made of it. During this waiting time, for example, an accumulator that is provided in the autonomous mobile unit can be charged or a self-diagnosis of the device can be undertaken.
One problem that occurs when docking such units is comprised therein that the device must be brought from an arbitrary starting configuration into a fully defined final position. Known autonomous mobile units as disclosed, for example, by German Patent P 44 21 805 orient themselves with ultrasound sensors and on the basis of odometry measurements that are undertaken at a wheel of the unit. While the device is travelling from a starting point to a destination point, the configuration errors produced by the sensor imprecisions in the odometry measurement and in the ultrasound distance measurement sum up, so that an exact orientation is soon no longer possible when no counter-measures are undertaken. In said patent, counter-measures are undertaken in such a form that different activities that the autonomous mobile unit is to perform are evaluated and the configuration errors are thereby monitored. Correction measures are initiated when too great an error occurs.
Another problem is comprised therein that the autonomous mobile unit should preferably dock in a docking station in a well-defined rotational orientation and with a very specific outside at the docking station. As a rule, however, such autonomous mobile units comprise a three-wheel kinematics which does not enable them to move arbitrarily on the ground. The three-wheel kinematics of autonomous mobile units is discussed, for example, in German Patent 195 21 358. The slippage that sums up over a planned travel path of such an autonomous mobile unit is thus determined therein.